Struct fuchsia_async::Task

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pub struct Task<T>(/* private fields */);
Expand description

This is the same as a JoinHandle, except that the future will be cancelled when the task is dropped.

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impl<T> Task<T>

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pub fn detach_on_drop(self) -> JoinHandle<T>

Returns a JoinHandle which will have detach-on-drop semantics.

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impl Task<()>

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pub fn detach(self)

Detach this task so that it can run independently in the background.

Note: this is usually not what you want. This API severs the control flow from the caller, making it impossible to return values (including errors). If your goal is to run multiple futures concurrently, consider using [TaskGroup] or other futures combinators such as:

  • [futures::future::join]
  • [futures::future::select]
  • [futures::select]

or their error-aware variants

  • [futures::future::try_join]
  • [futures::future::try_select]

or their stream counterparts

  • [futures::stream::StreamExt::for_each]
  • [futures::stream::StreamExt::for_each_concurrent]
  • [futures::stream::TryStreamExt::try_for_each]
  • [futures::stream::TryStreamExt::try_for_each_concurrent]

can meet your needs.

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impl<T: Send + 'static> Task<T>

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pub fn spawn(future: impl Future<Output = T> + Send + 'static) -> Task<T>

Spawn a new task on the current executor.

The task may be executed on any thread(s) owned by the current executor. See Task::local for an equivalent that ensures locality.

The passed future will live until either (a) the future completes, (b) the returned Task is dropped while the executor is running, or (c) the executor is destroyed; whichever comes first.

§Panics

spawn may panic if not called in the context of an executor (e.g. within a call to run or run_singlethreaded).

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impl<T: 'static> Task<T>

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pub fn local(future: impl Future<Output = T> + 'static) -> Task<T>

Spawn a new task on the thread local executor.

The passed future will live until either (a) the future completes, (b) the returned Task is dropped while the executor is running, or (c) the executor is destroyed; whichever comes first.

NOTE: This is not supported with a [SendExecutor] and will cause a runtime panic. Use Task::spawn instead.

§Panics

local may panic if not called in the context of a local executor (e.g. within a call to run or run_singlethreaded).

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impl<T: 'static> Task<T>

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pub fn cancel(self) -> impl Future<Output = Option<T>>

Cancel a task and returns a future that resolves once the cancellation is complete. The future can be ignored in which case the task will still be cancelled.

Trait Implementations§

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impl<T: Debug> Debug for Task<T>

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fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more
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impl<T> Drop for Task<T>

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<T> From<JoinHandle<T>> for Task<T>

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fn from(value: JoinHandle<T>) -> Self

Converts to this type from the input type.
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impl<T: 'static> Future for Task<T>

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type Output = T

The type of value produced on completion.
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fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available. Read more

Auto Trait Implementations§

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impl<T> Freeze for Task<T>

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impl<T> !RefUnwindSafe for Task<T>

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impl<T> Send for Task<T>
where T: Send,

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impl<T> Sync for Task<T>
where T: Sync,

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impl<T> Unpin for Task<T>

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impl<T> !UnwindSafe for Task<T>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FutureExt for T
where T: Future + ?Sized,

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fn map<U, F>(self, f: F) -> Map<Self, F>
where F: FnOnce(Self::Output) -> U, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
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fn map_into<U>(self) -> MapInto<Self, U>
where Self::Output: Into<U>, Self: Sized,

Map this future’s output to a different type, returning a new future of the resulting type. Read more
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fn then<Fut, F>(self, f: F) -> Then<Self, Fut, F>
where F: FnOnce(Self::Output) -> Fut, Fut: Future, Self: Sized,

Chain on a computation for when a future finished, passing the result of the future to the provided closure f. Read more
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fn left_future<B>(self) -> Either<Self, B>
where B: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the left-hand variant of that Either. Read more
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fn right_future<A>(self) -> Either<A, Self>
where A: Future<Output = Self::Output>, Self: Sized,

Wrap this future in an Either future, making it the right-hand variant of that Either. Read more
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fn into_stream(self) -> IntoStream<Self>
where Self: Sized,

Convert this future into a single element stream. Read more
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fn flatten(self) -> Flatten<Self>
where Self::Output: Future, Self: Sized,

Flatten the execution of this future when the output of this future is itself another future. Read more
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fn flatten_stream(self) -> FlattenStream<Self>
where Self::Output: Stream, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
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fn fuse(self) -> Fuse<Self>
where Self: Sized,

Fuse a future such that poll will never again be called once it has completed. This method can be used to turn any Future into a FusedFuture. Read more
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fn inspect<F>(self, f: F) -> Inspect<Self, F>
where F: FnOnce(&Self::Output), Self: Sized,

Do something with the output of a future before passing it on. Read more
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fn catch_unwind(self) -> CatchUnwind<Self>
where Self: Sized + UnwindSafe,

Catches unwinding panics while polling the future. Read more
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fn shared(self) -> Shared<Self>
where Self: Sized, Self::Output: Clone,

Create a cloneable handle to this future where all handles will resolve to the same result. Read more
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fn remote_handle(self) -> (Remote<Self>, RemoteHandle<Self::Output>)
where Self: Sized,

Turn this future into a future that yields () on completion and sends its output to another future on a separate task. Read more
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fn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + Send + 'a>>
where Self: Sized + Send + 'a,

Wrap the future in a Box, pinning it. Read more
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fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>
where Self: Sized + 'a,

Wrap the future in a Box, pinning it. Read more
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fn unit_error(self) -> UnitError<Self>
where Self: Sized,

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fn never_error(self) -> NeverError<Self>
where Self: Sized,

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fn poll_unpin(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
where Self: Unpin,

A convenience for calling Future::poll on Unpin future types.
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fn now_or_never(self) -> Option<Self::Output>
where Self: Sized,

Evaluates and consumes the future, returning the resulting output if the future is ready after the first call to Future::poll. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<F> IntoFuture for F
where F: Future,

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type Output = <F as Future>::Output

The output that the future will produce on completion.
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type IntoFuture = F

Which kind of future are we turning this into?
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fn into_future(self) -> <F as IntoFuture>::IntoFuture

Creates a future from a value. Read more
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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<F> TimeoutExt for F
where F: Future,

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fn on_timeout<WT, OT>(self, time: WT, on_timeout: OT) -> OnTimeout<Self, OT>
where WT: WakeupTime, OT: FnOnce() -> Self::Output,

Wraps the future in a timeout, calling on_timeout to produce a result when the timeout occurs.
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fn on_stalled<OS>( self, timeout: Duration, on_stalled: OS, ) -> OnStalled<Self, OS>
where OS: FnOnce() -> Self::Output,

Wraps the future in a stall-guard, calling on_stalled to produce a result when the future hasn’t been otherwise polled within the timeout. This is a heuristic - spurious wakeups will keep the detection from triggering, and moving all work to external tasks or threads with force the triggering early.
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<F, T, E> TryFuture for F
where F: Future<Output = Result<T, E>> + ?Sized,

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type Ok = T

The type of successful values yielded by this future
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type Error = E

The type of failures yielded by this future
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fn try_poll( self: Pin<&mut F>, cx: &mut Context<'_>, ) -> Poll<<F as Future>::Output>

Poll this TryFuture as if it were a Future. Read more
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impl<Fut> TryFutureExt for Fut
where Fut: TryFuture + ?Sized,

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fn flatten_sink<Item>(self) -> FlattenSink<Self, Self::Ok>
where Self::Ok: Sink<Item, Error = Self::Error>, Self: Sized,

Flattens the execution of this future when the successful result of this future is a [Sink]. Read more
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fn map_ok<T, F>(self, f: F) -> MapOk<Self, F>
where F: FnOnce(Self::Ok) -> T, Self: Sized,

Maps this future’s success value to a different value. Read more
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fn map_ok_or_else<T, E, F>(self, e: E, f: F) -> MapOkOrElse<Self, F, E>
where F: FnOnce(Self::Ok) -> T, E: FnOnce(Self::Error) -> T, Self: Sized,

Maps this future’s success value to a different value, and permits for error handling resulting in the same type. Read more
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fn map_err<E, F>(self, f: F) -> MapErr<Self, F>
where F: FnOnce(Self::Error) -> E, Self: Sized,

Maps this future’s error value to a different value. Read more
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fn err_into<E>(self) -> ErrInto<Self, E>
where Self: Sized, Self::Error: Into<E>,

Maps this future’s Error to a new error type using the Into trait. Read more
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fn ok_into<U>(self) -> OkInto<Self, U>
where Self: Sized, Self::Ok: Into<U>,

Maps this future’s Ok to a new type using the Into trait.
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fn and_then<Fut, F>(self, f: F) -> AndThen<Self, Fut, F>
where F: FnOnce(Self::Ok) -> Fut, Fut: TryFuture<Error = Self::Error>, Self: Sized,

Executes another future after this one resolves successfully. The success value is passed to a closure to create this subsequent future. Read more
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fn or_else<Fut, F>(self, f: F) -> OrElse<Self, Fut, F>
where F: FnOnce(Self::Error) -> Fut, Fut: TryFuture<Ok = Self::Ok>, Self: Sized,

Executes another future if this one resolves to an error. The error value is passed to a closure to create this subsequent future. Read more
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fn inspect_ok<F>(self, f: F) -> InspectOk<Self, F>
where F: FnOnce(&Self::Ok), Self: Sized,

Do something with the success value of a future before passing it on. Read more
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fn inspect_err<F>(self, f: F) -> InspectErr<Self, F>
where F: FnOnce(&Self::Error), Self: Sized,

Do something with the error value of a future before passing it on. Read more
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fn try_flatten(self) -> TryFlatten<Self, Self::Ok>
where Self::Ok: TryFuture<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is another future. Read more
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fn try_flatten_stream(self) -> TryFlattenStream<Self>
where Self::Ok: TryStream<Error = Self::Error>, Self: Sized,

Flatten the execution of this future when the successful result of this future is a stream. Read more
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fn unwrap_or_else<F>(self, f: F) -> UnwrapOrElse<Self, F>
where Self: Sized, F: FnOnce(Self::Error) -> Self::Ok,

Unwraps this future’s output, producing a future with this future’s Ok type as its Output type. Read more
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fn into_future(self) -> IntoFuture<Self>
where Self: Sized,

Wraps a [TryFuture] into a type that implements Future. Read more
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fn try_poll_unpin( &mut self, cx: &mut Context<'_>, ) -> Poll<Result<Self::Ok, Self::Error>>
where Self: Unpin,

A convenience method for calling [TryFuture::try_poll] on Unpin future types.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.